Determination of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn) by ICP-OES and their speciation in Algerian Mediterranean Sea sediments after a five-stage sequential extraction procedure

Abstract

Surface sediment samples (n = 18) were collected from the Algerian Mediterranean coasts and analyzed for seven metals using inductively coupled plasma-optical emission spectrometry in order to asses the distribution and bioavailability of metals and to study the anthropogenic factors affecting their concentrations. Sediment samples were size-fractionated into three sizes: 1,080-500 (coarse), 500-250 (medium), and <250 mm (fine). Bulk sediments were subjected to both sequential extraction and total digestion to evaluate the reliability of the sequential extraction procedure (SEP), while the fractions have been only sequentially extracted for metals speciation. The metals were sequentially extracted into five phases namely exchangeable (P1), carbonates (P2), Fe-Mn oxides (P3), organic (P4) and residual (P5). Metal recoveries in sequential extractions were +/-20% of the independently measured total metal concentrations; the high recovery rates indicate the good reliability of the SEP used in this study. Correlation coefficients indicated that the grain size has an effect on the distribution of metals in the investigated samples. The order of metal levels in the fractions was medium > fine > coarse for all the metals. The average total extractable metal concentrations for Cd, Cr, Cu, Fe, Ni, Pb, and Zn were 1.1, 8.8, 4.7, 1,291.3, 13.9, 5.7 and 20.4 mug/g, respectively. The northeastern shelf had the lowest metal levels while the highest were in northwestern part mainly due to the significant tourism activities in the northwestern part. Comparison of our results to Earth's crust values and to previous studies points out that our samples were relatively unpolluted with respect to the heavy metals investigated; most of the metals are not from anthropogenic sources. Enrichment factors as the criteria for examining the impact of the anthropogenic sources of heavy metals were calculated, and it was observed that the investigated samples were not contaminated with Cr, Cu, and Fe, moderately contaminated with Ni, Pb, and Cd, and contaminated with Cd in some sites. The P5 phase had the highest percents of Cr, Cu, Fe, Ni, and Zn. Cadmium and lead were predominant in the P4 phase, while Cu, Fe and Zn were distributed in the order P5 > P3 > P4 > P2 > P1. The following order of bioavailability was found with the heavy metals Pb > Cr > Cd > Ni > Zn > Cu > Fe.

Use of artificial sediment to assess toxicity of chromium on Chironomus xanthus, Danio rerio and Poecilia reticulata

“…According to Alomary and Belhadj (2007) the bioavailability of an element decreases with decreasing exchangeable for residual phases. The authors conducted a study in order to investigate the distribution of metals in sediment fractions of the Mediterranean Sea, and found that most metals predominate in F5 and smaller percentages are related to F1 and F2.…”

Fractionation and mobility of cadmium and lead in soils of Amol area in Iran, using the modified BCR sequential extraction method

“…The behavior of the elements in the environment cannot be reliably predicted assuming their total concentration (Alomary and Belhadj, 2007;Relic et al, 2010). Mobility and bioavailability of heavy metals in soil is determined by their chemical forms (Jaradat et al, 2006;Umoren and Udousoro, 2009).…”

Risk assessment of exposure to particulate output of a demolition site

“…It can be observed that the general trend for the major constituents is Si (Chen et al 2012;Cesari et al 2012 and references therein). It is generally accepted that the large concentrations of these elements are mainly due to their crustal abundance (Alomary and Belhadj 2007;Gunawardana et al 2012). In general, trace element concentrations are slightly more subject to variance because the sources are usually of an anthropogenic nature, and henceforth are highly dependent on the local sources of inputs (Amato et al 2009a).…”